Particle breakage is commonly observed in granular materials when subjected to external loads. It was found that particle breakage would occur during both sample preparation and loading stages. However,main attention ...Particle breakage is commonly observed in granular materials when subjected to external loads. It was found that particle breakage would occur during both sample preparation and loading stages. However,main attention was usually paid to the particle breakage behaviour of samples during loading stage. This study attempts to explore the breakage behaviour of granular materials during sample preparation.Triaxial samples of rockfill aggregates are prepared by layered compaction method to achieve different relative densities. Extents of particle breakage based on the gradings before and after test are presented and analysed. It is found that particle breakage during sample preparation cannot be ignored. Gradings after test are observed to shift away from the initial grading. Aggregates with larger size that appear to break are more than the smaller-sized ones. Irrespective of the initial gradings, an increase in the extent of particle breakage with the increasing relative density is observed during sample preparation.展开更多
In the zones of high seismic activity, tailings dam should be assessed for the stability against earthquake forces. In the present paper, a simplified method is proposed to compute the factor of safety of tailings dam...In the zones of high seismic activity, tailings dam should be assessed for the stability against earthquake forces. In the present paper, a simplified method is proposed to compute the factor of safety of tailings dams. The strain-dependent dynamic properties are used to assess the stability of tailings dams under seismic conditions. The effect of foundation soil properties on the seismic stability of tailings dams is studied using the proposed method. For the given input parameters, the factor of safety for lowfrequency input motions is nearly 26% lower than that for high-frequency input excitations. The impedance ratio and the depth of foundation have significant effect on the seismic factor of safety of tailings dams. The results from the proposed method are well compared with the existing pseudo-static method of analysis. Tailings dams are vulnerable to damage for low-frequency input motions.展开更多
Grading has long been recognised to critically influence the mechanical behaviour of ballast.To identify the ballast grading for heavy-haul rail track,monotonic and cyclic triaxial tests are conducted to assess the pe...Grading has long been recognised to critically influence the mechanical behaviour of ballast.To identify the ballast grading for heavy-haul rail track,monotonic and cyclic triaxial tests are conducted to assess the performances of different gradings.Permanent deformations,aggregates degradation,resilience,shear resistance,maximum and minimum densities are recorded and analysed.The grading is found to affect the behaviour of ballast in that coarser gradings exhibit relatively better strength,resilience and therefore less permanent deformation.However,ballast degradation increases with the overall aggregate size.Therefore,to identify the grading for ballast with different performance objectives,a grey relational theory is used to convert the multi-objective into single-objective,i.e.grey relational grade.A relatively optimal grading that provides the highest grey relational grade is thus suggested for the improved ballast performance.展开更多
基金supports provided by the Fundamental Research Funds for the Central Universities (Grant No. 2017B05214)
文摘Particle breakage is commonly observed in granular materials when subjected to external loads. It was found that particle breakage would occur during both sample preparation and loading stages. However,main attention was usually paid to the particle breakage behaviour of samples during loading stage. This study attempts to explore the breakage behaviour of granular materials during sample preparation.Triaxial samples of rockfill aggregates are prepared by layered compaction method to achieve different relative densities. Extents of particle breakage based on the gradings before and after test are presented and analysed. It is found that particle breakage during sample preparation cannot be ignored. Gradings after test are observed to shift away from the initial grading. Aggregates with larger size that appear to break are more than the smaller-sized ones. Irrespective of the initial gradings, an increase in the extent of particle breakage with the increasing relative density is observed during sample preparation.
文摘In the zones of high seismic activity, tailings dam should be assessed for the stability against earthquake forces. In the present paper, a simplified method is proposed to compute the factor of safety of tailings dams. The strain-dependent dynamic properties are used to assess the stability of tailings dams under seismic conditions. The effect of foundation soil properties on the seismic stability of tailings dams is studied using the proposed method. For the given input parameters, the factor of safety for lowfrequency input motions is nearly 26% lower than that for high-frequency input excitations. The impedance ratio and the depth of foundation have significant effect on the seismic factor of safety of tailings dams. The results from the proposed method are well compared with the existing pseudo-static method of analysis. Tailings dams are vulnerable to damage for low-frequency input motions.
基金co-sponsored by the Centre for Geomechanics & Railway Engineering of the University of Wollongongfinancial support provided by the Fundamental Research Funds for the Central Universities(Grant No.2017B05214)the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘Grading has long been recognised to critically influence the mechanical behaviour of ballast.To identify the ballast grading for heavy-haul rail track,monotonic and cyclic triaxial tests are conducted to assess the performances of different gradings.Permanent deformations,aggregates degradation,resilience,shear resistance,maximum and minimum densities are recorded and analysed.The grading is found to affect the behaviour of ballast in that coarser gradings exhibit relatively better strength,resilience and therefore less permanent deformation.However,ballast degradation increases with the overall aggregate size.Therefore,to identify the grading for ballast with different performance objectives,a grey relational theory is used to convert the multi-objective into single-objective,i.e.grey relational grade.A relatively optimal grading that provides the highest grey relational grade is thus suggested for the improved ballast performance.
